An Israeli ground invasion of Lebanon could trigger doomsday scenes and all out war, a senior diplomat has said as the IDF could come face-to-face with troops trained by Britain.

The Middle Eastern country's London ambassador Rami Mortada has said their troops would not 'stand idly by and watch' if Israel invaded or were to 'mount a heavy aerial attack', The Times reports.  

Last night, Israeli jets pummeled Lebanon with more than 100 strikes - despite calls for restraint amid fears of a spiraling conflict within the Middle East following a week of pager and walkie-talkie blasts which has left the country in disarray.

The bombardment marked the nation's most intense hit on Lebanon for nearly a year while world leaders gathered in Paris to urgently call for de-escalation.

Mr Mortada warned that Hezbollah has become a 'formidable fighting force' - saying that a multi-frontal war in the region could radicalise a whole new generation in Europe.

He told the broadsheet: 'We are facing all the risks of an all-out regional conflict and that's what we have been tirelessly trying to avoid.

Israel's bombardment of targets across Lebanon came hours after British Foreign Secretary David Lammy urged UK citizens to leave the country.

'My message to British nationals in Lebanon is leave while commercial options remain. Tensions are high and the situation could deteriorate rapidly,' he wrote on X. 

'Let's hope that we don't get there because this is a doomsday scenario for everyone. It's definitely a doomsday for Lebanon but Lebanon will not hurt alone in this war. That's what recent history taught us. So all efforts should be focused on avoiding such an outcome.'

The diplomat continued: 'There are many dangerous aspects for the Middle East that could get as far as Europe and beyond.' 

David Lammy urgently called for British nationals to flee the region last night amid fears the 'situation could deteriorate rapidly', revealing he had spoken to Lebanon's PM Najib Mikati and 'expressed my deep concern over rising tensions and civilian casualties'.

And the White House said a diplomatic solution was achievable and urgent, with a spokesperson telling a briefing it is 'afraid and concerned about potential escalation'.

The intense barrage followed attacks earlier in the week attributed by Lebanon and Hezbollah to Israel that blew up Hezbollah radios and pagers, killing 37 people and wounding about 3,000 in Lebanon.

In Thursday's late operation, Israel's military said its jets struck hundreds of multiple-rocket-launcher barrels in southern Lebanon that were set to be fired immediately toward Israel in a strike that lasted two hours.

The bombardment included more than 52 strikes across southern Lebanon after 9 p.m, Lebanon's state news agency NNA said. 

Three Lebanese security sources said these were the heaviest aerial strikes since the conflict began in October.

There were no immediate reports of casualties.

Israel's military vowed to continue to attack Hezbollah and said its strikes throughout Thursday hit about 100 rocket launchers plus other targets in southern Lebanon.

In a TV address yesterday, Hezbollah leader Hassan Nasrallah said the device explosions on Tuesday and Wednesday 'crossed all red lines'.

'The enemy went beyond all controls, laws and morals,' he said, adding the attacks 'could be considered war crimes or a declaration of war.'

He further acknowledged that the proscribed terrorist group had suffered an 'unprecedented' blow when thousands of operatives' communication devices exploded.

Describing the attacks as a 'massacre' and a possible 'act of war', Nasrallah said Israel would face 'tough retribution and just punishment, where it expects it and where it does not'.

But even as he delivered his televised address, Israeli warplanes could be heard breaking the sound barrier over Beirut. 

Iran-backed Hezbollah is an ally of Palestinian militant group Hamas, which has been fighting a war in Gaza since its October 7 attack on Israel.

For nearly a year, the focus of Israel's firepower has been on Gaza but its troops have also been engaged in near-daily clashes with Hezbollah militants along its northern border.

Hundreds have been killed in Lebanon, most of them fighters, and dozens in Israel, including soldiers.

The exchanges of fire have forced tens of thousands of people on both sides of the border to flee their homes.

Nasrallah vowed to keep up Hezbollah's fight against Israel until a ceasefire in Gaza is reached. Hamas welcomed the promise of support.

Hezbollah said 25 of its members had been killed in the device explosions, with a source close to the group saying at least 20 had died when their walkie-talkies blew up. 

Foreign Minister Abdallah Bou Habib said the 'blatant assault on Lebanon's sovereignty and security' was a dangerous development that could 'signal a wider war'.

Speaking ahead of a UN Security Council meeting on the attacks set for Friday, he said Lebanon had filed a complaint against 'Israel's cyber-terrorist aggression that amounts to a war crime'.

Iran's Revolutionary Guards said Israel faces 'a crushing response from the resistance front' after the blasts, which wounded Tehran's ambassador in Beirut.

US Secretary of State Antony Blinken, who has been scrambling to salvage efforts for a Gaza ceasefire and hostage release deal, called for restraint by all sides.

'We don't want to see any escalatory actions by any party' that would endanger the goal of a ceasefire in Gaza, he said as he joined European foreign ministers in Paris to discuss the widening crisis.

Press Secretary Karine Jean-Pierre said President Joe Biden still believes there can be a diplomatic solution between Israel and Hezbollah. 'He believes it's achievable,' she told a briefing.

Palestinian president Mahmud Abbas, in Madrid, called for a new peace conference aimed at ending the Israeli-Palestinian conflict.

Israel has not directly commented on the pager and radio detonations, which security sources say were probably carried out by its Mossad spy agency. The shadowy organisation has a long history of carrying out sophisticated attacks on foreign soil.

The Lebanese mission to the U.N. said in a letter to the Security Council that Israel was responsible for detonating the devices via electronic messages and explosives implanted in them before they arrived in Lebanon, in line with theories that have circulated since the explosions.

The 15-member Security Council will meet tomorrow over the blasts. Lebanese Prime Minister Najib Mikati called on the Security Council to take a firm stand to stop Israel's 'aggression' and 'technological war'.

Israeli Defence Minister Yoav Gallant said late on Thursday that Israel will keep up military action against Hezbollah.

'In the new phase of the war there are significant opportunities but also significant risks. Hezbollah feels that it is being persecuted and the sequence of military actions will continue,' Gallant said in a statement.

'Our goal is to ensure the safe return of Israel's northern communities to their homes. As time goes by, Hezbollah will pay an increasing price,' Gallant said.

Prime Minister Benjamin Netanyahu convened his close circle of ministers for consultations, Israel's Channel 13 News reported.

Two Israeli soldiers were killed in combat on Thursday in Israel's north, the Israeli military said.